Economic Assessment of Initial Cell Mass Increase in Maize Hydrolysate Fermentation for Ethanol Production

Increasing the cell mass used as an inoculum is an effective strategy for enhancing productivity in alcoholic fermentation processes. In batch processes without cell recycling, such as those used in maize ethanol production, this objective can be achieved through two main approaches: (i) increasing the amount of commercially acquired dry cell mass or (ii) extending the propagation time. In this study, an economic assessment of both approaches was carried out, considering the Brazilian industrial context of maize ethanol production. Fermentation assays demonstrated that specific substrate consumption decreases with increasing initial cell concentration, following a hyperbolic model. This experimental behavior was used to simulate different operational scenarios and estimate productivity gains and economic impacts. The results showed that both strategies increase ethanol production and revenue, although the associated costs vary significantly. Based on this model, productivity and revenue gains were estimated for both approaches. The findings suggest that extending the propagation time is the most economically viable strategy to increase the initial cell concentration, even in scenarios where the plant lacks existing infrastructure and additional equipment investments are required. The analysis also accounted for operational costs associated with increased energy consumption during extended aeration time.